Aquila Audax

The wedge-tailed eagle (''Aquila audax'') is the largest bird of prey in the continent of Australia. It is also found in southern New Guinea to the north and is distributed as far south as the state of Tasmania. Adults of this species have long, broad wings, fully feathered legs, an unmistakable wedge-shaped tail, an elongated maxilla, a strong beak and powerful feet. The wedge-tailed eagle is one of 12 species of large, predominantly dark-coloured booted eagles in the genus '' Aquila'' found worldwide. Genetic research has clearly indicated that the wedge-tailed eagle is fairly closely-related to other, generally large members of the ''Aquila'' genus.Lerner, H., Christidis, L., Gamauf, A., Griffiths, C., Haring, E., Huddleston, C.J., Kabra, S., Kocum, A., Krosby, M., Kvaloy, K., Mindell, D., Rasmussen, P., Rov, N., Wadleigh, R., Wink, M. & Gjershaug, J.O. (2017). ''Phylogeny and new taxonomy of the Booted Eagles (Accipitriformes: Aquilinae)''. Zootaxa, 4216(4), 301–320. A large brown-to-black bird of prey, it has a maximum reported wingspan of and a length of up to .

The wedge-tailed eagle is one of its native continent's most generalized birds of prey.Debus, S. (2017). ''Australasian Eagles and Eagle-like Birds''. CSIRO Publishing. They reside in most habitats present in Australia, ranging from desert and semi-desert to plains to mountainous areas to forest, even sometimes tropical rainforests. Preferred habitats, however, tend towards those that have a fairly varied topography including rocky areas, some open terrain and native woodlots such as ''Eucalyptus'' stands.Olsen, P. (2005). ''Wedge-tailed Eagle''. Australian Natural History Series. CSIRO Publishing.

The wedge-tailed eagle is one of the world's most powerful avian predators. Although a true generalist which hunts a wide range of prey, including birds, reptiles and, rarely, other taxa, this species is by and large a mammal predator.Olsen, J. (2014). ''Australian High Country Raptors''. CSIRO Publishing. The introduction of the European rabbit (''Oryctolagus cuniculus'') has been a boon to the wedge-tailed eagle and they hunt these and other invasive species in large volume, although the wedge-tailed eagle otherwise generally lives off of marsupials, including many surprisingly large macropods. Additionally, wedge-tailed eagles often eat not inconsiderable amounts of carrion, especially while young.Brown, L, & Amadon, D. (1986) ''Eagles, Hawks and Falcons of the World''. The Wellfleet Press. . Wedge-tailed eagles tend to pair for several years, possibly mating for life.

This species generally constructs a large stick nest in an ample tree, normally the largest in a stand, and lays typically two, although sometimes 1 to 4, eggs. Usually breeding efforts manage to produce one or two fledglings, which after a few months more tend to disperse widely. Nesting failures are usually attributable to human interference such as logging activity and other alterations, which both degrade habitats and cause disturbances. This species is known to be highly sensitive to human disturbance at the nest, which may lead to abandonment of the young. Bekessy, S. A., Wintle, B. A., Gordon, A., Fox, J. C., Chisholm, R., Brown, B., Regan, T., Mooney, N., Read, S. & Burgman, M. A. (2009). ''Modelling human impacts on the Tasmanian wedge-tailed eagle (Aquila audax fleayi)''. Biological conservation, 142(11), 2438–2448. Although historically heavily persecuted by humans via poisonings and shootings, mostly for alleged predation on sheep, wedge-tailed eagles have proved to be exceptionally resilient and have quickly rebounded to similar or even higher than pre-colonization numbers, thanks in part to humans inadvertently providing several food sources such as rabbits and large volumes of roadkills.Knobel, J. (2015). ''The conservation status of the Wedge-tailed Eagle in Australian law and thoughts on the value of early legal intervention in the conservation of a species''. De Jure Law Journal, 48(2), 293–311.

Taxonomy

The species was first described by the English ornithologist John Latham in 1801 under the binomial name ''Vultur audax''. The genus ''Vultur'' is today used only for a completely unrelated bird of the New World vulture family, the Andean condor (''Vultur gryphus'').Mindell, D. P., Fuchs, J., & Johnson, J. A. (2018). ''Phylogeny, taxonomy, and geographic diversity of diurnal raptors: Falconiformes, Accipitriformes, and Cathartiformes''. In Birds of prey (pp. 3–32). Springer, Cham. The specific scientific name for the species ''audax'', is derived from the Latin ''audac'', meaning “bold”, indicative of the perceived disposition of these raptors, perhaps when hunting (although ironically this species is in general highly wary otherwise and even “timid” towards humans). At one time, the wedge-tailed eagle was classified in it is own monotypical genus ''Uroaetus'', perhaps due to its unique form. However, this species is clearly quite similar, in many respects of morphology, appearance, behaviour and life history, to other species in the ''Aquila'' genus.Global Raptor Information Network. 2021. Species account: ''Wedge-tailed Eagle Aquila audax''. Downloaded from http://www.globalraptors.org on 4 November 2021 The eagles of the ''Aquila'' genus are part of the subfamily Aquilinae, within the larger Accipitridae family. The subfamily is commonly referred to as booted eagles or sometimes as true eagles. These species may be distinguished from most other accipitrids by the feathering covering their legs, regardless of distribution. With some 39 or so species, the Aquilinae is distributed on every continent, excluding Antarctica.

Via a variety of phylogenetic testing, largely via Mitochondrial DNA and Nuclear DNA genes, it has been determined that the wedge-tailed eagle clusters with certain other ''Aquila'' eagles. The species found to share the most genetic similarities is the Verreaux's eagle (''Aquila verreauxii'') of Africa. However, the Gurney's eagle (''Aquila gurneyi''), a mostly allopatric but outwardly fairly similar eagle is clearly a very close relation of the wedge-tailed eagle and the two are likely sister species, most likely originating from the same radiation across the Indo-Pacific region.Lerner, H. R., & Mindell, D. P. (2005). ''Phylogeny of eagles, Old World vultures, and other Accipitridae based on Nuclear and Mitochondrial DNA''. Molecular phylogenetics and evolution, 37(2), 327–346. These species, the wedge-tailed, Gurney's and Verreaux's eagles, form a clade or a species complex with the well-known golden eagle (''Aquila chrysaetos''), the most widely distributed species in the entire accipitrid family, as well as outwardly dissimilar (smaller and paler-bellied yet also powerful) eagles like the Bonelli's eagle (''Aquila fasciata''), the African hawk-eagle (''Aquila spilogaster'') and the Cassin's hawk-eagle (''Aquila africanus''), the latter three having once been considered members of a different genus. Beyond the aforementioned species, the four other ''Aquila'' species while outwardly similar to eagles such as golden and wedge-tailed eagles, being large, dark and brownish with long wings, are thought to form a separate clade based on genetic testing and are paraphyletic from the members of what can be called the golden eagle clade.Helbig, A. J., Kocum, A., Seibold, I., & Braun, M. J. (2005). ''A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level''. Molecular phylogenetics and evolution, 35(1), 147–164. Other related outliers from, currently from outside the ''Aquila'' genus, are the small-to-mid-sized '' Clanga'' or spotted eagle species and the widely found and quite small ''Hieraeetus'' eagles. One member of the latter genus contains the only other widely found Aquilinae eagle in Australia, the little eagle (''Hieraaetus morphnoides'').

Subspecies

Two subspecies of wedge-tailed eagle are recognized. However, the separation of the two subspecies has been called into question, largely because the reported differences in both size and coloration can be attributed to clinal variation and some of the insular populations may still be at an intermediate stage of subspecific formation.Austin, J. J., Olivier, L., Nankervis, D., Brown, W. E., Gardner, M. G., & Burridge, C. P. (2014). ''Twenty microsatellite loci for population and conservation genetic studies of the wedge-tailed eagle (Aquila audax)''. Australian Journal of Zoology, 62(3), 235–237.
* ''A. a. audax'' (Latham, 1801) – This subspecies resides in the entire continent of Australia as well as in southern New Guinea. It is the typical wedge-tailed eagle as subsequently described.
* '' A. a. fleayi'' ( Condon & Amadon, 1954) – This race is endemic to Tasmania. The subspecies is named in honour of David Fleay, an Australian naturalist who was the first to propose the difference of the insular race. ''A. a. fleayi'' differs from mainland wedge-tailed eagles mainly via size and colouring. It is larger than mainland eagle and is said to have particularly outsize mainland eagles in talon dimensions.Pay, J. M., Katzner, T. E., Wiersma, J. M., Brown, W. E., Hawkins, C. E., Proft, K. M., & Cameron, E. Z. (2021). ''Morphometric Sex Identification of Nestling and Free-Flying Tasmanian Wedge-Tailed Eagles (Aquila audax fleayi)''. Journal of Raptor Research. Furthermore, it is a deep chocolate brown colour rather than blackish in overall colour with a whitish buff colouring to the nape rather than tawny-rufous feathers there. The juvenile is altogether paler and sandier than equivalent aged wedge-tailed eagle on mainland Australia. Although the validity of the subspecies has been questioned, genetic studies have determined that there is no gene flow or introgression between Tasmanian and other wedge-tailed eagles; furthermore, the insular race was likely formed by marine dispersals, a process wedge-tailed eagles may continue to engage in despite usually avoiding large bodies of water, albeit usually in narrower straits.Burridge, C. P., Brown, W. E., Wadley, J., Nankervis, D. L., Olivier, L., Gardner, M. G., Barbour, R. & Austin, J. J. (2013). ''Did postglacial sea-level changes initiate the evolutionary divergence of a Tasmanian endemic raptor from its mainland relative?'' Proceedings of the Royal Society B: Biological Sciences, 280(1773), 20132448.

Description

This is a very large and quite lanky eagle. It is characteristically black but can appear tar to charcoal brown depending on lighting and individual variation. Wedge-tailed eagles have a massive bill but possess a relatively small and rather flat head with a long, almost vulturine neck. Furthermore, they are distinctive for their prominent carpals and baggy feathered trousers. The species tends to perch conspicuously on dead trees, telegraph poles, rocks or the open ground at times. Between the bill size, elongated shape and prominent shoulders this species is highly distinctive, with its long wings extend well down long and markedly wedge-tipped tail while perched. They have a large proportion of bare facial skin is thought to be an adaptation to the warm climate not to carrion eating, as the non-carrion eating Verreaux's eagle has similar facial feathering and the golden eagle eats carrion too. Against the blackish plumage, the tawny-rufous hackles on the neck, forming a lanceolated shape, as well as the pale brown to rufous crissum and narrow mottled grey-brown band across the greater wing coverts all stand out well. The sexes are indistinguishable by plumage. The juvenile is mainly darkish brown with extensive rufous feather edging and a paler, fairly streaky head. Furthermore, the juvenile has a lighter brown crissum, light reddish brown to golden nape with similar colouring extending sometimes to the back and wing band. The wing band is considerably more prominent than those of adults, extending to the median and sometimes the lesser coverts. Rarely, a juvenile may be all dull black, lacking rufous edges or a wing band. The young eagles are much the same by the 2nd through the 4th years though may be almost invariably visibly in moult and with a narrowing wing band. They become darker around the 5th year with a red-brown nape and a still narrowing wing band. Full mature plumage is not attained until the 7th or 8th year, although sexual maturity can be considered as early as 5. Adults have dark brown eyes, while the juvenile has similar but usually slightly darker eyes. Wedge-tailed eagles are typically creamy white on the cere and feet although these can be dull yellow, more so in juveniles than adults. The wedge-tailed eagle has a unique moult process in that they moult almost continuously and very slowly, and it may take 3 or more years for an eagle of the species to complete a moult. Moults are arrested only at times of famine and happen so gradually as to not impede the flight or hunting capacities of an eagle.

In flight, wedge-tailed eagles appear as a very large dark raptor with a well-protruding head, long and relatively narrow-looking wings more or less parallel edged when soaring and most distinctly a long diamond-shaped tail. The shape is fairly dissimilar from any other raptor in the world.Recher, H. F. (2020). ''The Australian Bird Guide: Revised Edition''. CSIRO Publishing. Juveniles tend to be broader winged in comparison. The wingspan is around 2.2 times greater than the total length. They tend to fly with rather loose but deep and powerful beats. Wedge-tailed eagles spend much time sailing along, looking quite stable and controlled even in strong winds. The species glides and soars on upswept wings with long splayed primaries often the ample tail may be upcurved at the edges often (or “dished”).Debus, S. (2019). ''Birds of Prey of Australia: a Field Guide''. CSIRO Publishing. The eagle often spreads its deep wing emarginations to reduce drag in high winds. Quite on the contrary to their superlative and controlled appearance once on the wing, flight for wedge-tailed eagles can be a struggle even in normal circumstances unless from it is from a pinnacle or somewhat windy and within the forest they may clamor about to reach the canopy with a "lack of grace". Gorged birds on the ground can be vulnerable due to being practically grounded, such as historically to Aboriginal hunters. Wedge-tailed eagles have been seen at more than in the air by human gliders. The adult is all blackish on the wing but for the tawny-rufous nape and greyish wing band (running less than a quarter of the way down the wing's width). Little relieves the dark coloration below but the pale brown to rufous crissum and the pale greyish bases to their flight feathers. Juvenile wedge-tailed eagles appear much browner although in general are not dissimilar in pattern below though the body and wings relative to adult. However, juveniles may show some paler mottling, of an off-rufous colour. Meanwhile, the juvenile's tail and most flight feathers are barred greyish which in turn contrast against the pale based primaries with black tips. Above, the juvenile bears much paler and more sandy rufous colour from the head to at least upper mantle and along broad wing band (as well as more than half the wing width). The lighter dorsal colour sometimes extends to much of the back and scapulars. Rare individual juvenile wedge-tailed eagles are dull black without wing band or paler edges. With much variation in individuals, generally as the young eagles age, the signature wing band shrinks incrementally and after 5th year the plumage darkens.

Size

The female wedge-tailed eagle is one of the world's largest eagles.Unwin, M., & Tipling, D. (2018). ''The Empire of the Eagle: An Illustrated Natural History''. Yale University Press. Its nearest rival in Australia for size is some 15% smaller linearly and 25% lighter in weight. As is typical in birds of prey, the female is larger than the male; although a few individuals are larger by only 0–17%, they average up to 33% larger. A full-grown female weighs between , while the smaller males weigh . Total length varies between and the wingspan typically is between . In 1930, the average weight and wingspans of 43 birds were and . The same average figures for a survey of 126 eagles in 1932 were and , respectively. According to one guide, the mean body mass of male wedge-tailed eagles is while that of females is listed as , which, if accurate, is one of the most extreme examples of size sexual dimorphism known in any bird of prey.Cherriman, S. C. (2007). ''Territory size and diet throughout the year of the Wedge-tailed Eagle Aquila audax in the Perth region, Western Australia''. B. Sc.(Hons) Thesis, Curtin University, Western Australia. However, another sample showed far less stark size differences, with 29 males weighing an average of and 29 females an average of . In the same sample, from the Nullarbor Plain, males averaged wingspan of (sample of 26) and body length of (sample 5) while females had an average wingspan of (sample 23) and body length of .Brooker, M. (1996). ''Morphometrics of the Wedge-tailed Eagle Aquila audax''. Corella, 20, 129–134. However, the Nullarbor Plain eagles appear slightly smaller than wedge-tailed eagle sizes from other surveys, based on body mass and wing chord sizes. An average length for males of and was described for wedge-tailed eagles in Queensland. Another source claimed an average male weight of and average female body mass of . Yet another book lists males as averaging and females as averaging . A sample of 10 males averaged while 19 females weighed .Parry, S. J. (2001). ''The booted eagles (Aves: Accipitridae): perspectives in evolutionary biology''. University of London, University College London (United Kingdom).Baker-Gabb, D. J. (1984). ''Morphometric data and dimorphism indices of some Australian raptors''. Corella, 8, 61–63. The mean body mass of males in Tasmania was while that for females was .

The largest wingspan ever verified for an eagle was for this species. A female killed in Tasmania in 1931 had a wingspan of , and another female measured barely smaller at . Similar claims, however, have been made for the Steller's sea eagle (''Haliaeetus pelagicus''), which has been said to reach or exceed in wingspan. Reported claims of wedge-tailed eagles spanning and were unverified and deemed to be unreliable per Guinness World Records. This eagle's great length and wingspan place it among the largest eagles in the world, but its wings, at more than , and tail, at up to , are unusually elongated for its body weight, and nine or ten other eagle species regularly outweigh it. It is around the third heaviest ''Aquila'' species, outsized only somewhat by the golden eagle and slightly by the Verreaux's eagle, although it only slightly exceeds the weight of the Spanish imperial eagle (''Aquila adalberti'').''CRC Handbook of Avian Body Masses, 2nd Edition'' by John B. Dunning Jr. (Editor). CRC Press (2008), . Among the entire booted eagle subfamily, in addition to the two heavier ''Aquila'', it is outsized in bulk by the martial eagle (''Polemaetus bellicosus''), while the also long-tailed crowned eagle (''Stephanoaetus coronatus'') can average of a roughly similar body mass to the wedge-tailed eagle, although the latter is marginally the heavier bird. The wedge-tailed is significantly exceeded in body mass by only a few eagles, especially the Steller's sea eagle and harpy eagle (''Harpia harpyja'') and somewhat so by the Philippine eagle (''Pithecophaga jefferyi''), the white-tailed eagle (''Haliaeetus albicilla'') and the bald eagle (''Haliaeetus leucocephalus''). However, it rivals the Steller's and harpy eagles and is known to be exceeded only by the Philippine eagle in total length. The wedge-tailed eagle's wingspan is the largest of any ''Aquila'', and is exceeded amongst all eagles probably only by the white-tailed and Steller's sea eagles in average spread though its average (not maximum) wingspan is rivaled by that of the martial eagle.Mendelsohn, J.M., Kemp, A.C., Biggs, H.C., Biggs, R., & Brown, C.J. (1989). ''Wing areas, wing loadings and wing spans of 66 species of African raptors''. Ostrich, 60(1), 35-42.

Among standard measurements, within the nominate subspecies, the wing chord of males may range from while that of the female is from . In Tasmania, the wing chord measured from in males and in females. In Nullarbor Plain, males averaged in wing chord while females averaged . Other Australian wedge-tailed eagles averaged in wing chord among males and among females. In Tasmania, the wing chord averaged in males and in females. The extreme tail length, slightly to greatly exceeding that of other ''Aquila'', is in males from , averaging in the Nullarbor eagles and in Tasmania, and from , averaging in Nullarbor and in Tasmania. Although they only slightly exceed in tail length the heavier two ''Aquila'' and crowned eagles and they can rival the tail lengths of the Philippine and the Harpiinae eagles, Tasmanian wedge-tailed eagles are quite likely to be the longest tailed of all modern eagles. The length of the tarsus may be from . The tarsus of 7 males averaged while that of 7 females averaged . In terms of bill measurements, the exposed culmen may range from in males and in females while total bill length (from the gape) is from and , in the sexes respectively. It is likely to be the largest billed ''Aquila'', a bit ahead of the imperial eagles and the Verreaux's eagle, behind only the larger ''Haliaeetus'' and Philippine eagles amongst all eagles. In Tasmania, culmen lengths averaged in males and in females while the total length of the bill averaged and . The hallux claw, the enlarged rear talon on the hind toe, is slightly smaller than that of a golden or Verreaux's eagle, even proportionately, but is by no mean small and is extremely sharp. According to one study, wedge-tailed eagles had a hallux claw of , ranging from , in males , ranging from in a sample of 10, in females. Another source listed the hallux claw of mainland Australian eagles as averaging in males and in females. Meanwhile, in Tasmanian eagles, the hallux claw averaged , ranging from , in males while in females the hallux claw averaged , ranging from . In terms of osteological structure and size, the wedge-tailed eagle is said to be proportional to other eagles, being notably smaller and less robust than the heaviest eagles such as Steller's and harpies but fairly similar in osteology in both structure and proportions to the golden eagle.

Identification

Their unique combination of large size, lanky build, long, diamond-shaped tail (though can be round-ended when both central feathers are moulted together), mainly black or rather dark plumage, and long wings seen when soaring or gliding make all ages of the wedge-tailed eagle fairly unmistakable in the majority of their range. The only main confusion species is often the black-breasted kite (''Hamirostra melanosternon''), which is surprisingly similar in colouring but is much smaller with a relatively short, squared tail and extensive clear white windows covering a good part of their wings. Juveniles of the white-bellied sea eagle (''Haliaeetus leucogaster''), at times mentioned as potentially confusable with a young wedge-tailed eagle, are much paler below with a rather different flight pattern: a short pale tail, bare legs, shorter, broader wings held in stiff dihedral. In New Guinea, the Gurney's eagle is more similar than those species in form and build but the Gurney's is somewhat smaller and more compact than the wedge-tailed eagle with rich yellow feet, a rather shorter rounded or faintly wedge-tipped tail, shorter and relatively broader wings (in adaptation to more forest-living).Beehler, B. M., & Pratt, T. K. (2016). ''Birds of New Guinea''. Princeton University Press. Furthermore, the Gurney's eagle has a much paler immature plumage. Although usually considered an island endemic, the Gurney's eagle is possibly capable of marine dispersals, as is the wedge-tailed eagle, that may lead to them to turn up in the forests of northern Australia and historical reports show that a rare vagrant of the species may indeed appear there. Papuan eagle (''Harpyopsis novaeguineae''), the only other island raptor in New Guinea that approaches the wedge-tailed in size is a highly distinct and forest-restricted species, being much paler, particularly below, with long bare legs and different proportions, more like a giant ''Accipiter'' with short rounded wings, a long, somewhat rounded tipped tail and a large, rounded head.

Vocalizations

The wedge-tailed eagle is not a bird well known for its vocalization nor are they often heard. They may be silent for long stretches of time, possibly months, at least outside of breeding season. When vocalizations have been documented, it usually only near the nest and in aerial display and can be hard to hear unless at close range. The commonest calls for wedge-tailed eagles are high, rather thin whistles, sometimes transcribed as ''I-see, I-see'' followed by a short descending ''see-tya''. Also documented during the breeding season are various other whistles, yelps and squeals and an often rolling series. Characteristically, all their calls are surprisingly weak though the main call is sometimes considered to have a “melancholy” quality. The opinion on their call is not dissimilar to the golden eagle, whose voice is similarly considered unimpressive. Female calls in wedge-tailed eagles are similar but are generally lower and harsher than males.

Range and habitat

Wedge-tailed eagles are found throughout Australia, including Tasmania and southern New Guinea in almost all habitats, though they tend to be more common in favourable habitat in southern and eastern Australia. In Australia, they may be found almost continuously all the way from the Cape York Peninsula in the north down to Wilsons Promontory National Park and Great Otway National Parks in the southern tips of the continent and from Shark Bay in the western side of the continent to Great Sandy National Park and Byron Bay in the east. They are widespread throughout the desert interior of Australia, however are rare or occur at low densities in the most arid parts of the continent, such as the Lake Eyre Basin. Offshore, the wedge-tailed eagle may be distributed in several of the larger and some of the smaller Australian islands. These include a majority of the Torres Strait Islands, Albany Island, Pipon Island, the isles of Bathurst Bay, many small isles in Queensland from Night Island down to the South Cumberland Islands, Fraser Island, Moreton Island, North Stradbroke Island, Montague Island, Kangaroo Island, the Nuyts Archipelago, Groote Eylandt and the Tiwi Islands. In Tasmania, they may be found essentially throughout as well as some isles of the Kent Group, Bass Strait, Flinders Island and Cape Barren Island.Fielding, M. W., Buettel, J. C., & Brook, B. W. (2020). ''Trophic rewilding of native extirpated predators on Bass Strait Islands could benefit woodland birds''. Emu-Austral Ornithology, 120(3), 260–262. In New Guinea, the wedge-tailed eagle is highly range restricted and can be found in predominantly in the Trans-Fly savanna and grasslands and the general area around the Western Province, as well as in the Merauke Regency, with some isolated reports in Western New Guinea, the Bensbach River and the Oriomo River.

Habitat

The wedge-tailed eagle inhabits an extremely wide range of habitats. Although range restricted relative to the golden eagle, it likely occupies a wider range of habitat types than likely any other ''Aquila'' eagle and indeed may outrival any booted eagle species in their usage of diverse habitats, being somewhat more akin to habitat generalist raptors such as ''Buteo'' buzzards. Assorted habitats known to host wedge-tailed eagles includes open woodland, savanna, heathland, grasslands, desert edge and semi-desert, subalpine forests, montane grasslands and mountain peaks, not-too-dense tropical rainforests, monsoon forests, dwarf conifer forests, some wetlands as well as regularly forays to coastal areas, though normally along the coasts they occur around plains somewhat away from the water. Favored habitat tends to be remote or rough country, at least partially wooded and not uncommonly varied with some rocky spots as well as in shrubland. Wedge-tailed eagles seem to prefer some dead trees to be present. They may occur around ''Eucalyptus'' woodland quite regularly, as well as ''Acacia'' woodland and mixed woodlands of ''Casuarina cristata-Flindersia maculosa-Callitris'' cypresses and also stands of ''Casuarina cunninghamiana''.Sharp, A., Norton, M., & Marks, A. (2001). ''Breeding activity, nest site selection and nest spacing of wedge-tailed eagles, Aquila audax, in western New South Wales''. Emu, 101(4), 323–328.Collins, L.., & Croft, D. B. (2007). ''Factors influencing chick survival in the Wedge-tailed Eagle Aquila audax''. Corella, 31, 32–40.Silva, L. M., & Croft, D. B. (2007). ''Nest-site selection, diet and parental care of the wedge-tailed eagle Aquila audax in western New South Wales''. Corella, 31(2), 23–31. A strong preference was detected for ''C. cunninghamiana'' alternatively with several ''Eucalyptus'' species was detected in the Australian Capital Territory, sloping ground allowing good access and access to tall, mature trees being paramount to the eagles in the study.Hatton, F., Mickan, P. H., Gruber, B., & Olsen, J. (2014). ''Modelling the nesting habitat requirements of the wedge-tailed eagle Aquila audax in the Australian Capital Territory using nest site characteristics''. Corella, 38, 63–70. Quite often they will be seen soaring over hills, mountains or escarpments as well as over flat plains, especially spinex grassland. Dense forest is typically avoided with glades and edge often sought out in forested areas. While they do occur in rich riparian woodlands, it is with relative scarcity despite this being where many other raptors of the nation concentrate.Aumann, T. (2001). ''An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia''. Wildlife Research, 28(4), 379–393. In the deserts of the Lake Eyre basin, they are often seen in gibber plains along treed watercourses and drainage basins, here often concentrated around ''Eucalyptus'' in stony creek beds. In the sandy desert areas of Western Australia, wedge-tailed eagles were once reasonably common but have largely vacated the region after the macropod prey they live off of there were all but hunted to extinction.Johnstone, R. E., & Storr, G. M. (1998). ''Handbook of Western Australian Birds (Vol. 2)''. Western Australian Museum. Wedge-tailed eagles commonly occur from sea level up to about with seemingly no preference based on altitudinal level. A fairly pronounced liking for mountainous localities such as plateaus has been detected in a few studies of wedge-tailed eagle. One of the few habitat types considered to be strongly avoided by wedge-tailed eagles are areas intensively settled or cultivated areas. A slightly fading tendency to avoid human areas has been detected, perhaps as persecution rates have gone far down, and the wedge-tailed eagle may be seen near towns and villages in exurban and even suburban areas largely within bushland. However, the species is seldom seen other than as a flyover in more developed towns and cities. Additionally, it is not uncommon in manmade spots such as pasture areas, forestry clearings, and rolling farmland areas.

Behaviour

This impressive bird of prey spends much of the day perching in trees, on rocks as well as similar exposed lookout sites such as cliffs from which it has a good view of its surroundings. Alternatively, they may sit on the ground for long periods of time or watch from a lower point, such as or termite mounds or anthills. Now and then, it takes off from its perch to fly low over its territory. Especially whilst not breeding, wedge-tailed eagles spends a considerable amount of the day on the wing. Wedge-tailed eagles are highly aerial, soaring for hours on end without wingbeat and seemingly without effort, regularly reaching and sometimes considerably higher. The purpose of soaring has received little specific study in wedge-tailed eagles, but it is likely, as in other accipitrids, in large part for surveying the territory and advertising their presence to other eagles. During the intense heat of the middle part of the day, it often soars high in the air, circling up on the thermal currents that rise from the ground below. Often when on the wing, it is scarcely visible to the human's naked eye. Their keen eyesight extends into ultraviolet bands. With a visual perception some three times more acute than those of humans, one of the largest pecten oculi of any bird and an eye roughly as big as a small human's, they may be one of the most sharp-eyed birds in the world. The wedge-tailed eagle is a largely sedentary as expected of a raptor dwelling in the subtropics, although they also dwell in the tropics (far northern Australia and New Guinea) as well as in the temperate zone (Tasmania). However, juveniles of the species can be quite dispersive. In some cases, they have moved to a recorded distance of some . These extreme movements have been completed within 7 to 8 months after dispersal. More typically they move no farther than or so. The adult eagles can also be nomadic, though only in circumstances such as drought conditions. In turn this explains the species presence in places they don't breed, even adults. In addition to moving for drought in arid zone, also moves in highest part of New South Wales, e.g. the Snowy Mountains, the species often apparently vacates snow-covered alpine zone in winter. The small New Guinea population is apparently indistinguishable from the mainland race and so possibly result of recent colonization, although no records exist of migrating wedge-tailed eagles islands past the Torres Straits. However, it can be projected from its presence in various offshore islands its capacity for crossing straits ranging up to as far as apart. One post dispersal young eagle was observed to distribute from Kangaroo Island to the mainland, possibly a regular occurrence.Debus, S. J. (2015). ''Assessment of band recoveries for three Australian eagle species''. Corella. Due to their tendency for wandering, some authors class the wedge-tailed eagles as a “ partial or irruptive migrant”. However, while they are arguably irruptive, it does not fit the mold of a true migrant well since under normal circumstances adults are rather sedentary unless environmental changes force them to move.

The wedge-tailed eagle is the only bird that has a reputation for not infrequently attacking hang gliders and paragliders, although other eagles including the golden eagle have also been recorded to behave thusly. Based on the response the eagles show to the gliders, they presumably are defending their territory and treating the perceived intruder like another eagle. Cases are recorded of the birds damaging the fabric of these gliders with their talons as well as some other parts of the gliding apparatus, but not the humans themselves, has been reported.Meredith, P. (1990). ''Encounters between Wedge-tailed Eagles and Hang-gliders''. Australian Bird Watcher, 13(5), 153–155. They have also been reported to attack and destroy unmanned aerial vehicles used for mining survey operations in Australia. The presence of a wedge-tailed eagle often causes panic among smaller birds, and as a result, aggressive species such as magpies (one of the most vulnerable types of passerine to eagle attacks), butcherbirds, wagtails, monarch flycatchers, lapwings, and miners as well as smaller birds of prey, including both accipitrids and falcons, any of which may aggressively mob eagles (see video). Multiple species may join the kerfuffle and mob them, especially while the eagles perched, often engaging in noisy calling, presumably meant to disorient the predator, and occasionally in physical attacks against the eagle, typically focused where the big, relatively lumbering eagles could not grasp the attacking birds. The wedge-tailed eagle usually does not engage its tormentors but sometimes rolls in the air to present talons whether perched or not. Sometimes wedge-tailed eagles appear to fight but this and other behaviours, especially between young eagles, may be interpreted as playful. Some such behaviours have included fetching sticks tossed by others, athletic flipping between juvenile eagles and even playing games with dogs, via floating above them until the dogs bark or leap then floating up until the dog settles and then repeating the “game”.

Flocking behaviour has been noted, similar to that of vultures (Cathartidae and Accipitridae) in other countries, when carrion is available.Bird watcher's Tasmanian wedge-tailed eagle photo shows group's vulture-like behaviour
Georgie Burgess, ABC News Online, 27 April 2022

File:Wedge-tailed Eagle dayboro.ogv, In flight, 'mobbed' by Australian magpie, Dayboro

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